Pop Up Domination & Theme Site Crash Issues

I installed pop up domination plugin and my site will now not allow me to make any changes or do any modifications in the theme or admin panel. The site is still live, however It will not allow for any changes to be made. Any suggestions as to how I can fix this problem. The error that Im getting is below.

Fatal error: Call to undefined function is_rtl() in /home/acannon/public_html/electrician/wp-includes/general-template.php on line 2102

Please sign in with the username and password you use to access the membership area (from where you downloaded the product(s) you purchased), and post your support request in the theme (which you are using) support forum.

In general, the quick fix is to simply delete the plugin directory from wp-content/plugins.